Background and Objectives: Tubular ectasia is a rare, pathologically benign condition which initially may present as tiny cyst. Knowledge of typical ultrasound features of this condition helps to differentiate it from other malignant lesions of testis. This study was conducted to find out ultrasound spectrum of tubular ectasia of rete testis and epididymis. Methods: Patients undergoing scrotal ultrasound and doppler for various indications including scrotal pain, infertility, postvasectomy and prior to recanalisation of vas were studied. The history, clinical examination, semen analysis and ultrasound features were analyzed. Our emphasis was on early detection of this rare but benign entity involving testis and epididymis. Results: Scrotal ultrasound with colour doppler in these patients revealed the abnormalities ranging from early changes like specked appearance and tiny cysts to more severe forms involving rete testis and epididymis. Associated abnormalities like epididymal cyst, hydrocele and spermatocele were also found in addition to tubular ectasia in some cases. Conclusion: Tubular ectasia is a pathologically benign condition which can be reliably diagnosed on ultrasound and colour doppler. Familiarity with the ultrasound and doppler features of tubular ectasia will definitely help in early diagnosis which in turn will help in reducing patients' anxiety and prevent unnecessary interventions.

Testicular lesions are often a source of great anxiety to patients. Since majority of testicular lesions are malignant, it is of utmost importance to diagnose benign lesions so that unnecessary investigations and harmful surgical interventions are avoided. Tubular ectasia of testis is such a benign condition which presents usually in patients in sixth decade of life. The presentation is usually asymptomatic swelling. Sometimes, this is diagnosed during workup of male infertility as tubular ectasia may be responsible for obstructive azoospermia. This may also be seen in patients who have undergone vasectomy for family planning purposes. Careful clinical history along with ultrasound examination with Doppler imaging will diagnose this condition in most of the patients and obviate the need for invasive procedures or orchidectomy for confirmation of diagnosis of malignant testicular tumors.

This paper is a pictorial essay on the ultrasound imaging of tubular ectasia of rete testis. As any “tumor” of testis is expected to provoke immense anxiety in patients, our emphasis in this pictorial review is on early diagnosis of tubular ectasia. An early diagnosis will help reduce the anxiety of patients and will obviate the need of further investigations and harmful interventions.

Pictorial Review

Scrotum contains a paired male reproductive organ called testis. The average volume of the testis in postpubertal age is approximately 25 mL. Usually, it measures 4–5 cm in length by 2.5–3 cm width. Its anteroposterior diameter is usually 3 cm. The epididymis is a comma-shaped, elongated structure situated on the posterior border of the testis. It is composed of three parts the head, body, and tail. The head of epididymis covers the upper pole of the testis. It receives the seminal fluid from the ducts of the testis. It allows the passage of the sperms into the distal portion of the epididymis. Epididymis contains sperms in different stages of maturation. It progressively goes on tapering and eventually turns into ductus deferens. On ultrasound epididymis, head (H) appears as isochoric pyramidal structure at superior pole of testis with echotexture coarser than testis. Narrow body (B) is usually indistinguishable from peritesticular tissue and tail (T) appears as curved structure at inferior pole [Figure 1].

Figure 1: Normal epididymis in a 30-year-old male. Longitudinal dual image scan of the left scrotum shows epididymis head (H) as isoechoic pyramidal structure at superior pole of testis with echotexture coarser than testis. Narrow body (B) usually indistinguishable from peritesticular tissue and tail (T) as curved structure at inferior pole

The rete testis is an anastomosing network of tubules located in the hilum. It carries sperm from the seminiferous tubules to the efferent ducts. On ultrasound, it appears as hypoechoic area adjacent to mediastinum testis with striated echotexture. It is the network of epithelium-lined spaces which are embedded within fibrous stroma of mediastinum testis [Figure 2].

Figure 2: Normal rete testis in a 25-year-old male patient. Longitudinal scan of the right scrotum reveals hypoechoic area adjacent to mediastinum testis with striated echotexture. It is the network of epithelium-lined spaces which are embedded fibrous stroma of mediastinum testis

Male infertility as a cause of primary or secondary infertility is increasing in recent days. With increasing awareness, its management is attaining a great significance. Obstructive azoospermia may be one of the causes of male infertility. Obstructive azoospermia due to any cause including postvasectomy cases may present as tubular ectasia of rete testis. The significance of identifying tubular ectasia and cystic changes in cases of infertility lies in the fact that its presence may provide a proof of continued spermatogenesis. These cysts can be a ready source of viable sperms. These patients can be subjected to procedures such as testicular sperm aspiration or percutaneous epididymal sperm aspiration followed by intracytoplasmic sperm injection. On ultrasound, obstructive azoospermia is frequently associated with tubular ectasia and cystic changes near mediastinum testis [Figure 3] and [Figure 4].

The occurrence of tubular ectasia is well known in patients who have undergone vasectomy for family planning purposes. The practice of tubectomy for family planning purposes has been widely prevalent in developing countries like India; however, with government encouraging vasectomy for family planning purposes, there is a gradual rise in vasectomy cases. Some of these patients over a period for some reasons, or other, request recanalization or reversal of vasectomy. Evaluation of these patients includes ultrasound. Ultrasound in these patients may show ectasia of rete testis in the form of tubular anechoic structures in rete testis [Figure 5] and [Figure 6].

The tubular ectasia of testis is usually asymptomatic and seen more frequently after 50 years of age. The etiology is varied but its commonly seen in postvasectomized patients. Sometimes, it may present as lump or scrotal discomfort. As expected any testicular swelling is bound to provoke immense anxiety in patients, and hence, it is important in patients presenting with lump or scrotal discomfort to rule out more sinister testicular lesions. On ultrasound, initially, fine low-level echoes may be noted which is consistent with speckled appearance. As the severity increases this speckled appearance may advance to dilated tubular channels at epididymis [Figure 7]a and [Figure 7]b.

Many conditions affecting testis may present with similar clinical features. Orchitis, epididymo-orchitis, testicular torsion, and malignant testicular tumors may all present with scrotal discomfort and pain. Ultrasonography with high-frequency transducer is the investigation of choice in all these conditions. The typical appearance of speckled appearance and anechoic channels at epididymis can lead to a diagnosis of tubular ectasia ruling out other conditions. This is crucial for further management of patient [Figure 8]a and [Figure 8]b.

Tubular ectasia is also reported in patients who have undergone abdominal and pelvic surgeries and after trauma. This is usually seen after abdominal surgeries such as abdominal hernia or rectal surgeries for malignancy. It is also seen in patients with hydrocele and those who are undergoing dialysis for chronic kidney disease. The cause of tubular ectasia in such patients is thought to be due to retention of calcium oxalate crystals. Any patient with scrotal pain with such past or present history should be evaluated by high-frequency ultrasound for tubular ectasia [Figure 9].

Figure 9: Mild cystic dilation of rete testis in a 41-year-old patient with history of inguinal hernia repair. Short-axis scan of the right testis show mild dilation of ducts at mediastinum testis

Tubular ectasia in many cases is associated with spermatocele. The spermatocele usually presents with a palpable mass. Since finding of spermatocele presenting with a palpable swelling needs to be differentiated from testicular tumors, these patients are usually referred for ultrasonography of scrotum. In patients with spermatocele ultrasonography of scrotum may show speckled and tubular anechoic structures in addition to spermatocele [Figure 10] and [Figure 11].

Figure 10: Tubular ectasia of epididymis and spermatocele in a 52-year-old male patient with palpable mass and pain. Panoramic view of the right scrotum shows moderately dilated anechoic, tortuous channels in spermatic cord region, and tubular ectasia epididymis head

In early stages, tubular ectasia may present as diffuse enlargement of epididymis. Magnified view of early tubular ectasia may show tiny low-level echoes along with enlarged epididymis. These echoes are due to multiple fluid interfaces between dilated ductules [Figure 12]a and [Figure 12]b.

It is important to differentiate tubular ectasia from intratesticular varicocele because of obvious implications of such a differentiation on management. Tubular ectasia can be differentiated from intratesticular varicocele by color Doppler. While color Doppler does not show any color flow in dilated tubules in case of tubular ectasia, in intratesticular varicocele, there is color flow in dilated tubules [Figure 13]a and [Figure 13]b.

Figure 13: (a) Color Doppler, axial scan of the right testis in a 42-year-old patient with scrotal pain shows small cyst at rete testis consistent with tubular ectasia. No color flow is noted in dilated tubule. (b) Color Doppler, axial scan of the left testis in 35-year-old patient for infertility evaluation shows color flow in dilated tubules suggestive of varicocele

Tubular ectasia of testis is a benign clinical condition which presents as cystic dilation of rete testis. It is usually seen in vasectomy patients presenting with scrotal discomfort, however, other causes of vas obstruction also lead to similar sonographic changes. The underlying mechanism of this cystic dilatation is complete or partial obstruction of the efferent ducts. These cysts usually contain spermatozoa and communicate with the tubular system.[1] Intratesticular obstruction is generally secondary to previous inflammatory insult such as orchitis, epididymo-orchitis. Extra-testicular obstruction can be secondary to trauma, postvasectomy, or other scrotal surgeries.[2] It is mostly found in older men, more than 55 years and the process is frequently bilateral.[3] Sometimes, tubular ectasia may be cause of obstructive azoospermia and may be responsible for infertility.[4] Spermatocele and epididymis cysts are commonly associated with this condition. The presentation is usually asymptomatic swelling. Tubular ectasia must be differentiated from malignant testicular tumors, especially those which are known to present as intratesticular cystic lesions such as teratomas.[5]

On ultrasound, the rete testis can be seen as ill-defined echo-poor region at testicular hilum with arboriform projections into the parenchyma.[6] In cases of tubular ectasia, ultrasound depicts multiple small tubular and cystic structures with fluid and hypoechoic contents involving the region of the rete testis. These hypoechoic and cystic lesions are found proximal to the mediastinum testis. The earliest presentation of ectasia seen in epididymis as enlargement and characteristic “ speckled appearance.” This speckled appearance is produced due to the presence of multiple cystic interfaces between walls of dilated ductules and fluid.[7] On color Doppler, there is no significant vascular flow within the lesion, and this feature helps to differentiate it from intratesticular vericocele.[8] On the contrary, on Doppler evaluation, if there is significant blood flow in the lesion which gets augmented on valsalva maneuver, then the possibility of intratesticular varicocele is more likely.[9] Epididymal cystadenoma, teratoma, non-Hodgkin's lymphoma, and testicular neoplasms causing secondary dilatation of seminiferous tubules.[10] Cystic dilatation noted in or adjacent to mediastinum testis as well as epididymal cysts are characteristics of tubular ectasia. These features aid to distinguish this benign condition from malignant cystic testicular tumors.[11]

Conclusion

Tubular ectasia of rete testis is a pathologically benign condition. It can be reliably diagnosed on clinical history, ultrasound imaging, and color Doppler. Familiarity with early ultrasound features of this condition may help early diagnosis which in turn may help reduce anxiety associated with testicular “tumor” and avoid unnecessary investigations and harmful interventions.